292 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



[Vol. 10 



indicated at first glance. There are 2 solutions under considera- 

 tion; one in which only dextrose was used as a source of carbo- 

 hydrate, the other with dextrose and the addition of a compara- 

 tively large amount of citric acid-potassium citrate mixture. 

 The alcoholic products occurred only where the citrate mixture 

 was present, except in the case of Oospora, and the natural in- 

 ference is that the citrate radical is the source of the products 

 formed. However, it is within the field of possibility that this 

 may not be the case, but that the strong buffer action of the 

 citrate mixture is successful in maintaining the reaction at an 

 unfavorable P H for a considerable time, which might result in an 

 abnormal metabolism of dextrose. However, in the Phomopsis 

 cultures only a small amount of dextrose was present with the 

 citrate mixture and this was soon utilized, probably before the 

 solution had acquired the semi-anaerobic condition. Likewise, 

 when the cultures of Aspergillus, which had been stoppered for 

 the aeration work and which contained only dextrose and pro- 

 duced no appreciable amount of alcoholic products, had citric 

 acid added to them after the dextrose was exhausted the odor of 

 alcohol rapidly developed. 



The question of buffering was raised primarily in connection 

 with Diplodia nalalensis. A series of flasks of the dextrose-citrate 

 solution was prepared but made too acid for the good growth of 

 this fungus. After inoculation the fungus developed very slowly 

 tufts of floating mycelium in the solution and after about 2 weeks 

 a small tuft on the surface. The odor of ethyl alcohol was very 

 ttrong, and there was also present some other substance of pene- 

 lrating odor but probably not acetic acid ; on distillation the distil- 

 sate gave an immediate and very strong iodoform test in the cold, 

 indicating that either acetone or isopropyl alcohol was probably 

 present. As no benzoyl chloride was available at the time no 



benzoate was made. The odor of the distillate, however, suggested 

 a mixture of ethyl alcohol and acetone together with some 



sub 



adjusted to a more favorable 



Ph did not produce these odorous compounds. The inference 

 here is that the buffering of the solution at an unfavorable P H 

 might be the important factor, but it is reasonable to suppose 

 that the buffering should affect the metabolism of the citrate 



